Monday, April 13, 2015

Transmissible cancer

Yikes. Yes, that is cancer that can be "contagious". This is different from oncoviruses, which are viruses that cause cancer (like some strains of HPV). But this is where a cancerous cells touching uninfected individuals can cause them to "catch" the cancer as well. Until recently, only three types were known (Spoiler alert/you can breath a sigh of relief: NONE in humans):

Facial tumors in tasmanian devils (DFTD), which are transmitted when these guys chomp each other in the face squabbling over food, mates, territory, and who's more swole.

I have spared you pictures of any of the above, but feel free to do a Google image search - NO! DO NOT DO A GOOGLE IMAGE SEARCH!

Line at the Mya arenaria clinic. Soft shell clams waiting for a blood/hemolymph draw to test for cancer, photo from Metzger via Cell Press. It really looks like proper science what with the lab diaper and flasks, beakers, and bunsen burner in the background.

Well, welcome to the club, Steamer! I agree that name is really inappropriately adorable for a leukemia, but it has been so dubbed because it infects soft-shell, or "steamer" clams (Mya arenaria). This leukemia have been observed for over 40 years, and causes death in the majority of individuals who become infected, but the cause of the leukemia was unknown until recently. The natural question here is: "Leukemia? Do clams even have blood?" And the answer is sort of - they have hemolymph, which is a fluid that carries oxygen (and other junx) around the tissues of the clam's open circulatory system.

Graphical abstract from Metzger et al. 2015 Cell. One of the key findings in this paper is that the tumors all had the same genetic signature in infected clams, suggesting that they all came from a single source, even though the clam populations examined were found hundreds of miles apart.

What/Who is Steamer? And how do I keep it the *bleep* away from me? Never fear! You won't have to give up your chowdah. Steamer is a "jumping gene", a retrotransposable element(2) that can get copied into the DNA of a host organism. If you can't imagine why mishmashing DNA could be problematic, everything you need to know on the topic can be found here. All kidding aside, let me be completely clear about this - this retrotransposon WILL NOT infect humans. But soft shell clams are indeed at risk. The most recent research shows that Steamer can travel hundreds of miles in the ocean and infect clams via these jumping genes. So, this is unusual because a virus is not spreading the disease but the tumor cells (hemocytes) themselves are spreading the disease. Hence: transmissible cancer.

It's certainly consoling that this newest discovery in the realm of terrifying things nature can kill you with is so distant from us in the tree of life that it's not a direct threat to us (lovers of clam chowder likely disagree, however. Disagreement noted.). Nonetheless, this is the first time a transmissible cancer has been discovered in an animal other than a mammal, which opens the possibility that there are many more of these out there infecting many more types of animals than we suspected.

Now try to sleep at night...

References and Miscellany:

1. It seems like this isn't a "naturally-occurring" transmissible cancer, in that the cancer was initially chemically induced, and then transmitted from one individual to another by injecting them with cells from the original tumor. So this isn't really quite the same thing, nonetheless, I'm including it here, because you will see it referenced in Wikipedia, and I wouldn't want you to think I didn't do my research. Also, be warned, the article I linked is pretty clinical.

2. Cripes, I am having a hard time finding relatable resources on retrotransposons! Try this? Entry level online resources describing this genetic process is absolutely a growth market. You could make a billion bucks if you made one decent you tube video on this topic. You're welcome.

Friday, April 3, 2015

It's after 4 on Friday, and I just spent a few hours trying to teach myself sql. Soooo ... brain. Because. But three easy pieces did cross into my field of view recently, and so:

1. Even extinct cone snails get all the attention!

Cone snails get a disproportionate amount of attention, mostly, I suppose because they are so diverse. Admittedly, they have some cool ecology, but nonetheless, those of us who don't work on them (or maybe just me) are sometimes a bit jealous of all the hubbub about a single group. So it was unsurprising when I saw this post from the Smithsonian blog about how entrancing even extinct cone snails are. A researcher from San Jose State University used UV light to show the color patterns on fossilized cone snail shells. Some of the pigmentation was no longer visible to the naked eye, but using this technique, this guy identified more than 10 new species! I feel like there should be some comment here about inspiration coming from the strangest places - like raves and velvet posters. Here's the original paper, with more cool photos.

2. Between a rock and a limpet radula

Well, Rah rah radula indeed! In fact, we had better hail the radula or it will come for us, and we will not come out on top. Engineers at the University of Portsmouth (also in Science Daily) have proclaimed that limpet teeth are made of the strongest naturally-occurring material known to man. Here, "strongest" refers to highest tensile strength and has nothing to do with towing a 767. For those of you who still think terrestrial systems have anything to offer ("But, but, what about spiders?") it turns out these fangs have toppled spider silk as the champion of natural material strength.

No, this picture does need to be this big. If the last post on attack snails wasn't enough to give you nightmares, this should be. Image from the University of Portsmouth.

All of that from this:

Patella vulgata, the common limpet. Just think about how strong teeth would be from an UNcommon limpet.Image from Wikimedia Commons.

3. Beauty abounds thanks to El Nino!

California faces drought unprecedented in recorded history and John Steinbeck wishes he were alive to document it. But Californians have something positive to look forward to - population booms of this beautiful slug, Okenia rosacea, which benefits from warmer temperatures. The Hopkins rose nudibranch is being spotted much further north than is usual. More from Science Daily and the primary literature.